Process of extracting arsenic, antimony, or tellurium from sulfurous ores.



No. 679,330. Patented July 30, i'90l.

' E. PETERSSUN.

PROCESS OF EXTRACTING ARSENIC, ANIIMONY, 0B TELLUBIUM FROM SULFURIIUSORES.

(Application filed Mar. 23, 1900.)

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ELIAS PETERSSON, OF BRUSSELS, BELGIUM, ASSIGNOR, BY MESNE ASSIGN- MENTS,TO THE INTRAOTABLE ORE TREATMENT COMPANY, LIMITED, OF

LONDON, ENGLAND.

PROCESS OF EXTRACTING ARSENIC, ANTIMONY, R TELLURIUM FROM SULFUROUSORES.

SPEGIFICATION formingpart of Letters Patent N 0. 679,330, dated July 30,1901. Application filed March 23,1900. Serial No. 9,957. (No specimens.)

To aZZ whom it may concern.-

Be it known that I, ELIAS PETERSSON, mining engineer, a subject of theKing of Sweden and Norway, residing at 32 Avenue de la C011- ronne,Brussels, in the Kingdom of Belgium,

have invented an Improved Process of Extracting Arsenic, Antimony, orTellurium from Sulfurous Ores Containing Them, of which the following isa specification.

In the specification accompanying my application filed December 30,1898, Serial No. 700,759, a process is described for treating orescontaining arsenic and antimony or tellurium in which the ores afterbeing pulverized and admixed with pulverized carbonaceous matter wereheated in a retort or muffle until the arsenic had been expelled andthen the ores were afterward treated in other ways to remove theantimony and tellurium and other metals contained in them.

According to the present invention the process as described inthe abovespecification is carried on until the arsenic has been expelled, andthen the mixed powdered ore and carbonaceous material contained in theretort or muffle are submitted to a still higher heat sufficient tovolatilize the antimony until the antimony and it may be also the bulkof the tellurium have also been driven off. The

ore in a finely-pulverized state is mixed with carbon, also reduced topowder, and the mixture is heated in a muffle-furnace first to atemperature sufficiently high'to volatilize or convert into vapor thearsenious and arsenic 3 5 sulfids, and when this has been done themuffle is still further heated to a higher temperature to volatilize orconvert into vapor the antimony in the form of antimonious sulfid.Preferably about ten per cent. of carbon, by

0 weight, or it may conveniently be such an amount of sawdust (or otherorganic material capable of yielding carbon by calcination) as will oncoking yield ten per cent. of carbon, is added to the ore; but theamount may be varied according to the nature of the ore, its oxygencontents, and its liability to melt.

Arsenic in the state of arsenious and arsenic sulfids is set free orvaporized at temperatures above 650 to 700 centigrade or higher,according to the nature of the ore and the composition of thearsenic-bearing minerals. If the temperature be raised still higher-2'.6., to a full red heatantimony as antimonious sulfid is volatilized.Both these substances are condensed in suitable cooling apparatus orcondensers either mixed or more or less separately by the use ofseparate condensers for the different ranges of tempera ture of thevolatilized substances.

Tellurium will be more or less volatilized, according to the nature oftelluride compound present. Possibly some tellurides, such as those oflead and bismuth, would not be de composed unless subjected to veryprolonged heating; but the tellurides of gold and silver would becompletely decomposed if submitted to a temperature sufficient tovolatilize sulfid of antimony during the period (some few hours) forwhich the mixture of carbon and pulverized ore is heated in the muffle,and 7c the tellurium would pass off either as a metallic vapor or avaporized compound containing some other component of the ore. Theprecious metals would therefore be left in a state in which they arethen readily recoverable. In this way both antimony and arsenic and thebulk of the tellurium may be removed by volatilization, either togetheror separately, and the gold left in the final residues may then beextracted by any convenient means, such as by amalgamation, cyanidation,or chlorination. If any traces of arsenic, antimony, or tellurium remainbehind after the volatilization process,they may (if found to hindergold extraction) be removed by an acid wash of dilute sulfuric orhydrochloric acid or bya short oxidizing calcination followed by an acidwash. If gold recovery is to be effected by chlorinatiomsuch a secondaryoxidizing calcination is neces o sary to remove the unburned carbon,which would interfere with the chlorinating operation and to a lessdegree with cyanidation. An oxidizing roast is also necessary beforerecovery of gold from the residues by chlorination or cyaniding, wherethe mineral originally treated contains other non volatile metallicsulfidssuch as iron, zinc, blande,

&c.which for all practical purposes remain unaltered when heatedwithcarbon to a temperature sufficientto volatilize antimony sulfid, butrequire to be roasted to their respective oxids' before submission togold-recovery processes If the mineral which is being treated shouldcontain small quantities of iron pyrites, some of the sulfur which itcontains would be driven off and would combine with the arsenic orantimony contained in the ore and pass off with it.

The carbon in addition to preventing oxidation of the sulfurets (by anyinlet leaks of air) also serves to insulate the particles of molten sulfidse. g., galena, antimonious.

sulfid, &c.and thus prevent the consequent clotting and clogging of thecharge. This is most important in dealing with readily-fusible minerals,and, moreover, is the chief factor in governing the amount of charcoal,carbon, or carbonaceous substance to be added. Now ten per cent. ofcarbon, it added in the form of charcoal or sawdust, is a veryconsiderable bulk of material compared with the bulk of mineral. Farless would do if it were meant merely to prevent oxidation; but in manycases less would be disadvantageous Where the mineral treated has atendency to melt together on heating. Again, carbon has a most importantbearing in its use with partially-oxidized ores, especially thosecontaining antimony.

Antimony oxid once formed is non-volatile. If antimony sulfid andantimony oxid were alone heated together, a portion of the antimonysulfid would volatilize, while a portion would be held back by the oxidas non-volatile antimony oxysulfid or antimony glass. Carbon preventsthis by reducing the nonvolatile oxid to volatile antimony metal andcarbonic-oxid gas, and thus permits oxidized ores to be handled whereotherwise impossible of successful volatilization treatment either inopen calcination or mufiies.

The extent to which the arsenical and antimonial ores are oxidized,governs to a small extent only the amount of carbon to be added, andpractically maybe ignored, as the amount of carbon added to preventmelting and running together of the ore will always be greatly in excessof that which could possibly be taken up by deoxidizing.

Ores of the character to which this invention relates are more or lessoxidized when they have lain for a long period of time at orsufficiently near the surface and have so been exposed to the action ofthe atmosphere.

The volatilized sulfurets of arsenic and antimony are much more readilycondensed when evolved as more or less concentrated vapors from a closedmuffle (or retort) than are the same metallic vapors, either as oxids orsulfurets or metal, if evolved in a gaseous current with other gases,either oxidizing (such as air) or inert, (such as carbonic oxid orcarbonic acid.) This readiness of condensation is very material, as thecondensed sulfurets command a high commercial value. Means must be takento prevent the inlet'of air into the condensersas, for instance, by thecommon expedient of having the end of the outdenser-pipe.

The following is given as an example of the driving off of antimony asantimonious-sulfid vapor from a mixed ore: Finely-crushed antimonialpyrites' mixed with ten per cent. .of sawdust heated for about one hourin a muffle-furnace at from 900 to 1,000 centigrade and the whole of theantimony sulfid was volatilized direct. On taking the hot material outof the muffle and simply rabbling in contact with air all the gold wassubsequently found to be extractable by cyanid.

Itis evident that the carbon employed might be replaced by other organicmattersas, for instance, sawdust-capable of yielding carbon bycalcination.

The condensed a light carbonaceous skeleton through the a briquets bythe charring thereof during the first stages of heating. Such materialsmay be tar, pitch, or molasses added in small percentages to the massduring mixing, the briquets being molded by hand or machinery andallowed to solidify sufficiently before charging into the muffie. Theadvantages gained by such briqueting are, first, greater uniformity ofcharge; second, the more economical application of the muifie-heat bythe avoidance of a thick dead non-conducting layer of powdery materialover the muffle-bottom; third, far easier escape for the volatilizedsulfuret vapors through the large interstices between the briquet's;fourth, the utilization of interior muffle-space to a far larger extentthan would be possible it merely powdered material were employed; fifth,the presentation of carbon formed during charring to every particle ofthe ore mass, and, sixth, the fixation of the non-volatile portion ofthe ore and prevention of mechanical loss therefrom during the escape ofvolatile material.

practice of this invention.

A is a retort heated by lines B, which surround it.

C is a vapor-outlet leading into a condens; ing-chamber D. E is a secondcondensingchamber, of which there may be one or more.

F-is a water-seal chamber containinglimewater.

G is an outlet from chamber F.

In the operation of this process carbon or organic material yieldingcarbon by calcination may be employed, and by the term carbonaceousmaterial employed in the claims I intend to include the use in theoperation of the process of either carbon or organic materialyielding'carbon on calcination.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, I declare thatwhat I claim is 1. A process for the removal of antimony and telluriumfrom sulfurous ores containing also arsenic, by direct volatilization,such process consisting in admixing the ore in a powdered state withpowdered carbonaceous material, heating the mixture while protected fromthe atmosphere to a temperature suflicient to volatilize such arsenic asmay be present as arsenious and arsenic sulfid, and further heating to ahigher temperature to volatilize the antimony as antimonious sulfid andalso drive ofl? the tellurium, but not to a temperature suflicient toeffect a substantial reduction of such remaining sulfids as may bepresent.

2. The process of treating sulfurous ores containing arsenic and one ormore other metals requiring higher temperature for volatilization, toseparate such components from the ore, which process consists in heatinga mixture of the pulverized ore and pulverized carbonaceous material ina retort or muffle furnace sufficiently to volatilize the arsenicsulfid, collecting such vapor in a condenser, further heating themixture to ahigher temperature to volatilize the remaining saidcomponent or components and collecting in a condenser the vapor thereof.

3. The process of treating sulfurous ores containing arsenic and one ormore other metals requiring higher temperature for volatilization, whichprocess consists in making carbonaceous material into blocks or bricks,and then heating said blocks or bricks in a retort or muffie,substantially as described, to separate the arsenic by volatilization,and further heating to a higher temperature to separate the other saidcomponent or components from the ore, but not to such temperature as toproduce substantial reduction of such remaining sulfids as may bepresent.

4:- The process of treating sulfurous ores containing arsenic and one ormore other metals requiringhigher temperatures for volatilization, toseparate such components from the ore, which process consists in makingup the ore when pulverized and admixed with carbonaceous material intoblocks or bricks, then heating such blocks to volatilize the arsenicsulfid, and further heating the blocks to a higher temperature tovolatilize the other said component or components, substantially asdescribed, but not to such temperature as to produce a substantialreduction of such remaining sulfids as may be present.

5. The process of treating sulfurous ores containing arsenic and one ormore other metals requiring higher temperatures for volatilization, toseparate such components from the ore, which process consists in heatingthe ore, when pulverized and mixed with pulverized carbonaceousmaterial, in a retort or muffie furnace to volatilize or drive off thearsenic sulfid, and then further heating the mixture to a highertemperature to volatilize or drive off the remaining said component orcomponents, but not to such temperature as to effect a substantialreduction of such remaining sulfids as may be present.

ELIAS PETERSSON.

Witnesses:

R. 13. RANsroRD, JOHN H. WHITEHEAD.

' up the ore when pulverized and admixed with

